1. Field of the invention
This invention relates generally to a deflection yoke for use with a color cathode ray tube so as to effect the scanning deflections of the electron beams generated therein, and more particularly is directed to a deflection yoke, as aforesaid, which is intended for use with an in-line color cathode ray tube, that is, a tube in which the plural electron beams originate in a common plane within the tube envelope.
2. Description of the Prior Art
Color cathode ray tubes or the so-called in-line type, that is, in which a plurality of electron beams originate in a common plane, for example, a horizontal plane, are now frequently employed, for example, in color television receivers and the like. In order to cause the electron beams to scan the screen of the color cathode ray tube, color cathode ray tubes of the in-line type are provided with a deflection yoke composed of a horizontal deflection winding producing a horizontal magnetic field of the pincushion type and a vertical deflection winding producing a vertical magnetic field of the barrel type for minimizing misconvergence of the electron beams. In most existing in-line color cathode ray tubes, a saddle shaped horizontal deflection winding and a toroidal vertical deflection winding are employed. However, the production of the deflection windings is substantially facilitated when both the horizontal and vertical deflection windings are saddle shaped.
Although saddle shaped horizontal and vertical deflection windings have been used in the deflection yoke for an in-line color cathode ray tube, and such deflection windings have been arranged to provide a horizontal deflection field of the pin-cushion type and a vertical deflection field of the barrel type, the resulting deflection yoke still causes misconvergence of the electron beams, particularly at the peripheral portions of the screen of the color cathode ray tube. In order to avoid such misconvergence, it has been the usual practice to employ a dynamic convergence correcting device in addition to the deflection yoke. However, such a dynamic convergence correcting device is troublesome to adjust and/or control and further results in increased cost of the color cathode ray tube.
In order to avoid the necessity for providing a dynamic convergence correcting device, it has also been proposed to provide an in-line color cathode ray tube with a deflection yoke in which the horizontal and vertical deflection windings are both toroidal and have specially arranged winding distributions by which the described misconvergence is eliminated. However, it is difficult to produce toroidal horizontal and vertical deflection windings with the required special distribution of the windings therein.